An optic disc of a retina is a portion where an optic nerve bundle enters into the deep portion of an eye. Since changes appear at the optic disc in a case of sickness such as glaucoma, it is diagnostically useful to determine the optic disc.
US Patent Application Publication No. 2007/0195269 discusses a technique for determining the optic disc region (also referred to as the “disc region”) by acquiring edges of the retinal pigment epithelium which is one of the layers in the retina. This technique is based on an anatomical feature that the retinal pigment epithelium does not exist directly under the vicinity of the optic disc center.
Japanese Patent Application Laid-Open No. 2008-73188 discusses a technique for determining a depression region at the optic disc based on the depth or distance from the anterior ocular segment to the fundus surface. This technique is based on the fact that the optic disc is a depression on the fundus surface.
Meanwhile, when determining the optic disc based on the fact that the retinal pigment epithelium does not exist, false images produced under blood vessels or lesions may make the retinal pigment epithelium unclear. Therefore, a region where the false images are produced may possibly be determined as the optic disc. Further, when determining the optic disc based on the surface shape of the retina, a depression other than the optic disc may possibly be determined as the optic disc.